Reactor system for preparing cyclohexylamine

Abstract

The utility model relates to a reactor system for preparing cyclohexylamine, and belongs to the technical field of chemical raw material synthesis. The reactor system for preparing cyclohexylamine comprises a fixed bed reactor, a flash tank, an ammonia absorption tower, a rectifying tower and a purifying tower, a gas feeding disc, an overflow groove type distributor and a catalyst bed layer are sequentially arranged in the fixed bed reactor from top to bottom, the top end of the fixed bed reactor is connected with an injection supercharger, a gas-liquid pipeline is connected between the injection supercharger and the fixed bed reactor, the gas-liquid pipeline is communicated with the interior of the fixed bed reactor, and the gas-liquid pipeline is communicated with the interior of the fixed bed reactor. A nozzle is arranged at the lower end of the gas feeding disc, the overflow groove type distributor comprises a distribution disc, an overflow distribution pipe is arranged on the distribution disc, the overflow distribution pipe is of a structure with an opening in the lower end, and overflow holes are formed in the pipe wall of the overflow distribution pipe. According to the system disclosed by the utility model, the p-phenylenediamine hydrogenation reaction is more thorough, the operation process is safe, the equipment is simple, the operation is convenient, and the cost is reduced.

Description

A reactor system for preparing cyclohexylamine Technical Field

[0001] This utility model relates to a reactor system for preparing cyclohexylamine, belonging to the field of chemical raw material synthesis technology. Background Technology

[0002] Cyclohexylamine is a widely used intermediate that can be used to produce vulcanization accelerators, desulfurizers, rubber antioxidants, chemical auxiliaries for plastics and textiles, latex coagulants, boiler feedwater treatment agents, metal corrosion inhibitors, antistatic agents, emulsifiers, preservatives, petroleum additives, pesticides, bactericides, and dye intermediates.

[0003] The existing process for producing cyclohexylamine is cumbersome, resulting in low product yield and high investment costs. Summary of the Invention

[0004] The present invention addresses the problems existing in the above-mentioned background technology by providing a reactor system for preparing cyclohexylamine by hydrogenation and deamination of p-phenylenediamine as a raw material.

[0005] To achieve the above objectives, the technical solution adopted is:

[0006] A reactor system for preparing cyclohexylamine includes a fixed-bed reactor, a flash tank, an ammonia absorption tower, a distillation tower, and a purification tower. The fixed-bed reactor is connected to a hydrogen feed pipe and a p-phenylenediamine feed pipe. From top to bottom, the fixed-bed reactor contains a gas feed pan, an overflow distributor, and a catalyst bed. The hydrogen feed pipe is connected to the gas feed pan. An ejector booster is connected to the top of the fixed-bed reactor. A gas-liquid pipeline connects the ejector booster to the fixed-bed reactor and is connected to the interior of the fixed-bed reactor. The fixed-bed reactor receives hydrogen gas via a bottom-outlet, top-inlet system. The circulation loop and liquid circulation loop are connected to the ejector booster. The lower end of the gas feed plate is equipped with a nozzle. The overflow trough distributor includes a distribution plate, and the distribution plate is equipped with an overflow distribution pipe. The overflow distribution pipe has an open structure at the lower end and overflow holes are provided on the pipe wall. The bottom of the fixed bed reactor is connected to the flash tank through a pipeline. The fixed bed reactor and the flash tank are respectively connected to the ammonia absorption tower through pipelines. The bottom of the flash tank is connected to the distillation column through a pipeline. The top of the distillation column is connected to the purification column through a pipeline. The top of the purification column is connected to the cyclohexylamine product outlet.

[0007] Based on the above technical solution, the present invention can be further improved as follows:

[0008] Preferably, the distribution plate is provided with multiple baffles, and a distribution groove is formed between adjacent baffles. The overflow distribution pipe is located in the distribution groove, and the top of the distribution pipe is provided with an oblique opening. A cover plate is provided above the oblique opening.

[0009] Preferably, the lower end of the gas-liquid pipeline is connected to an inlet diffuser, which is located inside the top inlet of the fixed-bed reactor.

[0010] The beneficial effects of adopting the above-mentioned preferred technical solution are as follows: After the ejector pressurizer mixes the introduced hydrogen gas with liquid p-phenylenediamine and the reaction circulating liquid, it enters the fixed bed reactor through the gas-liquid pipeline. The gas-liquid mixture is dispersed by the inlet diffuser and then evenly sprayed onto the overflow trough distributor. Multiple overflow distribution pipes are distributed in the distribution trough of the distributor. The pipe wall of the overflow distribution pipe is provided with overflow holes. When the liquid level in the distribution trough reaches a certain height, it can enter the overflow distribution pipe through the overflow holes and flow into the catalyst bed below. The overflow distribution pipe has an oblique opening, which is a gas channel, so that the hydrogen gas above can enter the overflow distribution pipe through the oblique opening and fully contact the liquid downward to react. The top of the overflow distribution pipe has a cover plate to prevent the liquid from directly entering the distribution pipe.

[0011] Preferably, the bottom of the distillation column is connected to a recycle pipe, which is connected to the liquid circulation loop.

[0012] The beneficial effects of adopting the above-mentioned preferred technical solution are as follows: the reprocessing pipeline returns the 1,4-cyclohexanediamine and unreacted p-phenylenediamine at the bottom of the distillation column to the liquid circulation loop for further reprocessing, thereby improving the yield.

[0013] More preferably, the distillation column is provided with a first top reflux pipeline at the top, and the purification column is provided with a second top reflux pipeline at the top. The first top reflux pipeline is provided with a first condenser, a first reflux tank, and a first circulation pump. The second top reflux pipeline is provided with a second condenser, a second reflux tank, and a second circulation pump. The reflux pipeline is provided with a third condenser, a third reflux tank, and a third circulation pump.

[0014] The beneficial effects of adopting the above-mentioned preferred technical solution are as follows: the first condenser condenses the vapor at the top of the distillation column, the first reflux tank collects the condensate, and the first circulating pump refluxes a portion of the condensate back to the top of the distillation column. This reflux operation can control the gas-liquid balance within the distillation column, improve the distillation efficiency, and enable the distillation column to more effectively separate substances with different boiling points. Similarly, the installation of the second condenser, the second reflux tank, and the second circulating pump ensures the reflux operation at the top of the purification column, which helps the purification column further purify the cyclohexylamine product and improve the product's purity.

[0015] Preferably, the overflow hole is arranged circumferentially along the wall of the overflow distribution pipe.

[0016] The advantages of adopting the above-mentioned preferred technical solution are that it enables the liquid to flow out more evenly in the overflow distribution pipe, thereby distributing it more evenly to the catalyst bed below, which is beneficial to improving the uniformity and efficiency of the reaction.

[0017] Preferably, the liquid circulation loop is equipped with a hydrogenation circulation pump and a circulation cooler, and the pipeline between the fixed bed reactor and the ammonia absorption tower is equipped with a release gas cooler.

[0018] The beneficial effect of adopting the above-mentioned preferred technical solution is that the circulating cooler and the release gas cooler play a cooling role.

[0019] Preferably, a flash condenser is provided on the pipeline between the flash tank and the ammonia absorption tower, and a fourth circulation pump is provided on the pipeline between the flash tank and the distillation tower.

[0020] The beneficial effects of adopting the above-mentioned preferred technical solution are as follows: the crude liquid product from the bottom of the fixed bed reactor is depressurized in the flash tank and then separated into gas and liquid. The gas is cooled by the flash condenser and then discharged to the ammonia absorption tower. The crude liquid product is then pumped by the fourth circulation pump to the distillation tower for distillation.

[0021] Preferably, the bottom of the purification tower is provided with a heavy component output pipeline, and a fifth circulation pump is provided on the heavy component output pipeline.

[0022] The beneficial effect of adopting the above-mentioned preferred technical solution is that the heavy component output pipeline outputs heavy component products such as 1,4-cyclohexanediamine under the power of the fifth circulation pump.

[0023] Preferably, the ammonia absorption tower is provided with an absorption circulation pipeline, a sixth circulation pump is provided on the absorption circulation pipeline, the absorption circulation pipeline is connected to an ammonia circulation liquid output pipeline, and a hydrogen-containing tail gas output pipeline is provided at the top of the ammonia absorption tower.

[0024] The beneficial effects of adopting the above-mentioned preferred technical solution are as follows: the sixth circulation pump and the absorption circulation pipeline promote the circulation and absorption of ammonia, ensure that ammonia and absorbent are in full contact, improve the absorption rate, reduce ammonia emission and environmental pollution, the ammonia circulation liquid output pipeline allows the recovery of ammonia-rich liquid for reuse, and the hydrogen-containing tail gas output pipeline treats unabsorbed gas, reduces waste and facilitates tail gas treatment.

[0025] Preferably, the gas feed plate includes a circular tube connected to each other, with nozzles connected to the lower part of the circular tube. The nozzles are symmetrically distributed on the circular tube, and each nozzle is a cylinder with a cone at the bottom. The diameter of the nozzle is 1 / 2 of the diameter of the circular tube. Holes are distributed in the fan-shaped part and the bottom of the cone, with the size of the opening being 1 / 4 of the diameter of the nozzle. There are 4 openings on the fan-shaped part, which are evenly distributed along the circumference of the fan-shaped part.

[0026] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0027] (1) The overflow trough distributor makes the liquid distribution in the cross section uniform, which is conducive to controlling the heat distribution and is less likely to cause uneven temperature distribution. It can indirectly extend the service life of the catalyst, reduce the generation of by-products, fully increase the material contact reaction area, and improve the mass and heat transfer efficiency.

[0028] (2) By using a circular tube and a perforated nozzle, the hydrogen feeding method is changed from a single location to a multi-location distribution, and a large flow of reaction gas is changed into multiple small flow gas streams, which fully increases the material contact reaction area;

[0029] (3) The ejector booster is the core equipment, which forms a local negative pressure, draws hydrogen from the bottom of the reactor into the gas chamber, and injects it together with the raw material mixture into the top of the fixed bed reactor. The mixture is then distributed by the overflow trough distributor to make the reaction mixture more uniform.

[0030] (4) By adopting the method of feeding the reaction circulating liquid and hydrogen in parallel, the temperature distribution in the fixed bed reactor can be controlled to a certain extent through continuous heat exchange, so that the entire reaction process can proceed along the optimal temperature sequence as much as possible, thereby improving the conversion rate and selectivity of the reaction.

[0031] (5) The system of this invention can make the hydrogenation reaction of p-phenylenediamine more thorough, the operation process is safe, the equipment is simple, the operation is convenient, and the cost is reduced. Attached Figure Description

[0032] Figure 1 is a schematic diagram of the reactor system for preparing cyclohexylamine according to this invention;

[0033] Figure 2 is a top view of the gas feed plate of this utility model;

[0034] Figure 3 is a top view of the overflow trough type distributor of this utility model;

[0035] Figure 4 is a front view of the overflow trough type distributor of this utility model;

[0036] Figure 5 is a schematic diagram of the overflow distribution pipe of this utility model;

[0037] The attached figures are labeled as follows: 11. Fixed-bed reactor; 102. Hydrogenation circulation pump; 103. Circulation cooler; 104. Ejector booster; 105. Release gas cooler; 111. Distribution plate; 112. Overflow distribution pipe; 1121. Overflow hole; 1122. Beveled opening; 1123. Cover plate; 113. Distribution trough; 114. Baffle; 115. Outer coil; 116. Inner coil; 21. Flash tank; 202. Flash evaporator Condenser; 203, Fourth Circulation Pump; 31, Ammonia Absorption Tower; 302, Sixth Circulation Pump; 41, Distillation Column; 411, First Condenser; 412, First Reflux Tank; 413, First Circulation Pump; 421, Third Reflux Tank; 422, Third Condenser; 423, Third Circulation Pump; 51, Purification Tower; 502, Fifth Circulation Pump; 511, Second Condenser; 512, Second Reflux Tank; 513, Second Circulation Pump. Detailed Implementation

[0038] The principles and features of this utility model are described below with reference to the accompanying drawings. The examples given are only for explaining this utility model and are not intended to limit the scope of this utility model.

[0039] As shown in Figures 1-5, a reactor system for preparing cyclohexylamine includes a fixed-bed reactor 11, a flash tank 21, an ammonia absorption tower 31, a distillation tower 41, and a purification tower 51. The fixed-bed reactor 11 is connected to a hydrogen feed pipe and a p-phenylenediamine feed pipe. From top to bottom, the fixed-bed reactor 11 contains a gas feed pan, an overflow distributor, and a catalyst bed. The hydrogen feed pipe is connected to the gas feed pan. An ejector booster 104 is connected to the top of the fixed-bed reactor 11. A gas-liquid pipeline connects the ejector booster to the fixed-bed reactor and is connected to the interior of the fixed-bed reactor. The fixed-bed reactor 11 is circulated with hydrogen gas flowing from bottom to top. The loop and liquid circulation loop are connected to the ejector booster 104. The lower end of the gas feed plate is provided with a nozzle. The overflow trough distributor includes a distribution plate 111. The distribution plate 111 is provided with an overflow distribution pipe 112. The overflow distribution pipe 112 has an open structure at the lower end. The pipe wall of the overflow distribution pipe 112 is provided with an overflow hole 1121. The bottom of the fixed bed reactor 11 is connected to the flash tank 21 through a pipeline. The fixed bed reactor 11 and the flash tank 21 are respectively connected to the ammonia absorption tower 31 through pipelines. The bottom of the flash tank 21 is connected to the distillation tower 41 through a pipeline. The top of the distillation tower 41 is connected to the purification tower 51 through a pipeline. The top of the purification tower 51 is connected to the cyclohexylamine product outlet.

[0040] In a preferred embodiment, the distribution plate 111 is provided with a plurality of baffles 114, and a distribution groove 113 is formed between adjacent baffles 114. The overflow distribution pipe 112 is located in the distribution groove 113, and the top of the overflow distribution pipe 112 is provided with a bevel 1122. A cover plate 1123 is provided above the bevel 1122.

[0041] In a preferred embodiment, the lower end of the gas-liquid pipeline is connected to an inlet diffuser, which is located inside the top inlet of the fixed bed reactor 11.

[0042] In a preferred embodiment, the bottom of the distillation column 41 is connected to a recycle pipe, which is connected to the liquid circulation loop.

[0043] In a preferred embodiment, the distillation column 41 is provided with a first top reflux pipeline at the top, and the purification column 51 is provided with a second top reflux pipeline at the top. The first top reflux pipeline is provided with a first condenser 411, a first reflux tank 412, and a first circulation pump 413. The second top reflux pipeline is provided with a second condenser 511, a second reflux tank 512, and a second circulation pump 513. The reflux pipeline is provided with a third condenser 422, a third reflux tank 421, and a third circulation pump 423.

[0044] In a preferred embodiment, the overflow hole 1121 is arranged circumferentially along the wall of the overflow distribution pipe 112.

[0045] In a preferred embodiment, the liquid circulation loop is equipped with a hydrogenation circulation pump 102 and a circulation cooler 103, and a release gas cooler 105 is provided on the pipeline between the fixed bed reactor 11 and the ammonia absorption tower 31.

[0046] In a preferred embodiment, a flash condenser 202 is provided on the pipeline between the flash tank 21 and the ammonia absorption tower 31, and a fourth circulation pump 203 is provided on the pipeline between the flash tank 21 and the distillation tower 41.

[0047] In this embodiment, the bottom of the purification tower 51 is provided with a heavy component output pipeline, and a fifth circulation pump 502 is provided on the heavy component output pipeline.

[0048] In this embodiment, the ammonia absorption tower 31 is provided with an absorption circulation pipeline, a sixth circulation pump 302 is provided on the absorption circulation pipeline, the absorption circulation pipeline is connected to an ammonia circulation liquid output pipeline, and a hydrogen-containing tail gas output pipeline is provided at the top of the ammonia absorption tower 31.

[0049] In this embodiment, the gas feed disc includes circular tubes that are connected to each other. Nozzles are connected to the lower part of the circular tubes and are symmetrically distributed on the tubes. Each nozzle is cylindrical with a conical bottom, and its diameter is half the diameter of the circular tube. Specifically, the diameter of the circular tube is 60mm, and the diameter of the nozzle is 30mm. The circular tube includes an outer circular tube 115 and an inner circular tube 116. Sixteen nozzles are symmetrically distributed on the outer circular tube 115, and eight nozzles are symmetrically distributed on the inner circular tube 116. Holes are distributed in the fan-shaped section and bottom of the conical section, with the opening size being one-quarter of the nozzle diameter. Four holes are opened on the fan-shaped section and evenly distributed along the circumference of the fan-shaped section, with a hole diameter of 5mm.

[0050] The specific production process is as follows:

[0051] 1. Add the nickel-ruthenium catalyst into the fixed-bed reactor 11. Specifically, it can be added through the gas-liquid pipeline. The filling method is random stacking. The upper layer filling height is 3.5 meters and the filling amount is about 7 tons. The lower layer filling height is also 3.5 meters and the filling amount is about 7 tons.

[0052] 2. Establish a reaction liquid circulation system. Introduce hydrogen from the hydrogen buffer tank and slowly heat the bottom of the fixed-bed reactor 11 to 150-160℃, controlling the heating rate to ≤30℃ / h. When the temperature reaches 150℃, pressurize the 150℃ liquid p-phenylenediamine with a pump and mix it with the reaction circulation liquid pumped out by the hydrogenation circulation pump 102. Then, the mixture enters the circulation cooler 103 and then enters the fixed-bed reactor 11 through the ejector booster 104. After two liquid distributions, the liquid drips evenly over the catalyst bed, and the p-phenylenediamine undergoes catalytic hydrogenation and deamination reaction on the catalyst surface. The temperature is controlled at 140℃, the pressure is controlled at 7.0 MPaG, and the amount of gas released is adjusted to control the deamination reaction.

[0053] 3. In the gas-liquid separation chamber at the bottom of the fixed bed reactor 11, the unreacted hydrogen is drawn back into the fixed bed reactor 11 by the ejector booster 104 to continue the reaction; the hydrogen and the removed ammonia are released as release gas, cooled by the release gas cooler 105, and then vented to the ammonia absorption tower 31 for recovery. The waste gas at the top of the ammonia absorption tower 31 is sent to the incinerator for treatment.

[0054] 4. The crude liquid product after hydrogenation reaction is depressurized in flash tank 21 and then subjected to gas-liquid separation. The gas is cooled by flash condenser 202 and then discharged to ammonia absorption tower 31. The crude liquid product is then distilled in distillation tower 41 to obtain crude cyclohexylamine, and then purified in purification tower 51 to obtain high-purity cyclohexylamine.

[0055] In this embodiment, a nickel-ruthenium catalyst is loaded into a fixed-bed reactor 11. The reaction pressure is 7 MPa(G), the temperature is 140°C, the p-phenylenediamine flow rate is 8000-10000 kg / h, the mass ratio of hydrogen to p-phenylenediamine is 1:17, and the reaction circulation flow rate is 400 m³ / h. Under the above conditions, a continuous hydrogenation reaction is carried out in the gas-liquid phase fixed-bed reactor 11 to obtain crude cyclohexane. The p-phenylenediamine conversion rate can reach 99.65%.

[0056] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A reactor system for the production of cyclohexylamine, characterized in that The reactor comprises a fixed-bed reactor, a flash tank, an ammonia absorption tower, a distillation tower, and a purification tower. The fixed-bed reactor is connected to a hydrogen feed pipe and a p-phenylenediamine feed pipe. From top to bottom, the fixed-bed reactor contains a gas feed pan, an overflow distributor, and a catalyst bed. The hydrogen feed pipe is connected to the gas feed pan. An ejector pressurizer is connected to the top of the fixed-bed reactor, and a gas-liquid pipeline connects the ejector pressurizer to the reactor. This gas-liquid pipeline is connected to the interior of the fixed-bed reactor. The fixed-bed reactor utilizes a bottom-out, top-in hydrogen circulation loop and a liquid circulation loop. The loop circuit is connected to the ejector booster. The lower end of the gas feed plate is equipped with a nozzle. The overflow trough distributor includes a distribution plate with an overflow distribution pipe on it. The overflow distribution pipe has an open lower end and an overflow hole on its wall. The bottom of the fixed bed reactor is connected to the flash tank via a pipeline. The fixed bed reactor and the flash tank are respectively connected to the ammonia absorption tower via pipelines. The bottom of the flash tank is connected to the distillation column via a pipeline. The top of the distillation column is connected to the purification column via a pipeline. The top of the purification column is connected to the cyclohexylamine product outlet.

2. The reactor system for preparing cyclohexylamine according to claim 1, characterized in that, The distribution plate is provided with a distribution groove, the overflow distribution pipe is located in the distribution groove, the top of the distribution pipe is provided with an oblique opening, and a cover plate is provided above the oblique opening.

3. The reactor system for preparing cyclohexylamine according to claim 1, wherein, The bottom of the distillation column is connected to a recycle pipe, which is connected to the liquid circulation loop.

4. The reactor system for preparing cyclohexylamine according to claim 3, characterized in that, The distillation column is provided with a first top reflux pipeline at the top, and the purification column is provided with a second top reflux pipeline at the top. The first top reflux pipeline is provided with a first condenser, a first reflux tank, and a first circulation pump. The second top reflux pipeline is provided with a second condenser, a second reflux tank, and a second circulation pump. The reflux pipeline is provided with a third condenser, a third reflux tank, and a third circulation pump.

5. The reactor system for preparing cyclohexylamine according to claim 1, characterized in that, The overflow hole is arranged circumferentially along the wall of the overflow distribution pipe.

6. The reactor system for preparing cyclohexylamine according to claim 1, wherein, The liquid circulation loop is equipped with a hydrogenation circulation pump and a circulation cooler, and the pipeline between the fixed bed reactor and the ammonia absorption tower is equipped with a release gas cooler.

7. The reactor system for preparing cyclohexylamine according to claim 1, wherein A flash condenser is installed on the pipeline between the flash tank and the ammonia absorption tower, and a fourth circulation pump is installed on the pipeline between the flash tank and the distillation tower.

8. The reactor system for preparing cyclohexylamine according to claim 1, wherein, The bottom of the purification tower is equipped with a heavy component output pipeline, and a fifth circulation pump is installed on the heavy component output pipeline.

9. The reactor system for preparing cyclohexylamine according to any one of claims 1-8, characterized in that, The ammonia absorption tower is equipped with an absorption circulation pipeline, a sixth circulation pump is installed on the absorption circulation pipeline, the absorption circulation pipeline is connected to an ammonia circulation liquid output pipeline, and a hydrogen-containing tail gas output pipeline is installed at the top of the ammonia absorption tower.

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